This invention relates to a rear wheel steering device for vehicles, particularly, to an improvement on a steering device which steers left and right rear wheels symmetrically in toe-in direction or toe-out direction.
A rear wheel steering device of this kind has been known, for example, Japanese Patent Application Laying Open Gazette No. 62-18309 discloses a device provided with a driving motor, a drive shaft connected to said motor to be driven through the medium of a gear mechanism and a pair (left and right) of screw feeding mechanism which transmits a rotary motion of the drive shaft as movement in axial direction (vehicle widthwise direction) of suspension arm members of left and right rear wheels, whereby left and right rear wheels are steered symmetrically in toe-in direction or toe-out direction according to vehicle velocity. Also, Japanese Patent Application Laying Open Gazette No. 59-23716 discloses a device which steers left and right rear wheels by two (left and right) hydraulic cylinders which are substituted for the driving motor mentioned above.
Of the conventional rear wheel steering devices mentioned above, in the case of the former two gear engaging parts (a screw feeding mechanism and a gear mechanism) are provided intermediately of a transmitting route between the motor and the rear wheel and backlash at each of such gear engaging parts can cause "shaking" in rear wheel steering. On the other hand, in the case of the latter because two (left and right) cylinders are controlled individually, it is difficult to synchronize suspension arm members of left and right rear wheels and the composition of hydraulic system which controls each hydraulic cylinder becomes complicated. Thus, the device itself becomes large in size and high in manufacturing cost.